1. Field of the Invention
This invention relates generally to locks. More particularly, this invention relates to locks that resist various destructive entry techniques such as shackle cutting or forcible blows and that are suitable for unguarded areas such as deserted storage facilities and the like. Known related art can be found in U.S. Classes 70, 292 and the related subclasses thereunder.
2. Description of Prior Art
As will be appreciated by those skilled in the art, the use of rented storage by society has grown tremendously during recent years, especially in large cities. A particularly popular enterprise comprises a large facility with several discrete temporary storage units that are individually leased to members of the general public. Each discrete storage unit typically comprises a single room accessed through a central door. Many municipalities have zoned or otherwise required such storage facilities to locate in industrialized sections or other areas that are often deserted or unattended at night. As a result, security at such facilities is often problematic.
While access to the facility as a whole may or may not be restricted in some manner, the individual renter is typically responsible for securing their rental unit against unauthorized entry. Since the doors on such storage units are often the only convenient entryways, most renters simply place a conventional padlock on the door to prevent unauthorized trespass or theft.
Unfortunately, unauthorized trespassers have discovered methods of disabling conventional padlocks. A favorite tactic of these dastardly villains is to use a bolt cutter, hack saw or another similar tool to cut through the exposed padlock shackles. Another favorite tactic is to forcibly strike the padlock housing with a large hammer or other blunt object to rip the shackles from the lock housing. Both of these practices of disabling padlocks are aided by the remote, deserted nature and lack of surveillance associated with many storage facilities.
Several prior art devices have been proposed to overcome the shortcomings associated with conventional padlocks on storage units. For example, U.S. Pat. No. 4,234,220 to Finch et al., shows an interesting lock wherein a conventional key lock case is inserted through an opening to engage at least two lugs. When the lock case is in the locking position, it prevents the bolt from moving to the left, thus maintaining the door in the locked position.
Another interesting example is shown in U.S. Pat. No. 5,404,734 to Martinez. The patent shows a specially designed lock case with an opening therethrough adapted to receive a bolt or other bar member having circular holes engaged by the internal mechanism in the lock body.
Yet another interesting example is shown in U.S. Pat. No. 4,802,351. This lock appears to employ a generally conventional lock case that blocks the end of a bolt. U.S. Pat. No. 2,974,987 to O'Brien also appears to use a generally conventional lock case to obstruct the motion of a sliding bolt. However, the lock case is received in and slides with the bolt and the case is arranged in a vertical position. Other prior art examples of general relevance can be seen in U.S. Pat. Nos. 2,722,819, 4,641,506 and 5,315,850.
However, none of the known prior art fails to provide acceptably tamper and/or cutter resistant locks that reliably preserve the integrity of remote doors. In particular, the known prior art fails to provide an apparatus that redundantly resists multiple types of destructive forces such as cutting instruments combined and/or forcible blunt blows.
Thus, a desirable improvement to the art would be a multiple redundancy lock that prevented unauthorized persons from disabling the lock by severing its shackles. Another desirable improvement would be a lock that transmitted forcible blows upon the tumbler housing directly to the door. Preferably, such a lock would adeptly deflect such forces from the pin by pivoting thereabout. An even more desirable lock would preserve the integrity of the door by preventing shackle severing and withstanding forcible blows. A desirable attribute of such an improved lock would be its increased durability and the increased integrity of the unit security.
Another desirable attribute of an improved lock would be an enclosed housing that prevented thieves from accessing the lock shackle(s) and/or mounting anchors that secure the lock to the door. Thus, thieves would be prevented from cutting the shackles or simply removing the lock from the door to gain access therein. Of course, an improved lock should be relatively simple to install with minimal tools and/or instructions.
Preferably, an improved lock could be retrofitted to existing storage unit doors to maximize the utility of existing structures without completely reinstalling the doors. As a consequence, the renter or owner would need only to remove the preexisting lock and install the improved lock to secure the facility.